The present invention relates to a microfluidic device for detecting a flow parameter, a microfluidic dosing system, a method for detecting a flow parameter of a fluid stream within a channel and to a method for microfluidically dosing a fluid. In particular, the present invention relates to a microdosing concept for dosing minute quantities of fluids, such as, for example, quantities of a liquid or gas, within a fluid channel.
In the field of medical technology, but also in other fields of technology, there is demand for dosing minute quantities or volumes of fluids (exemplarily in the range of nanoliters to microliters) with sufficient precision, and additionally also for being able to monitor this precise dosing process in terms of measuring technology.
Micromembrane or microdiaphragm pumps, for example, are employed in the field of medical technology for dosing carrier liquids or drugs, such as, for example, for infusions. At present, micromembrane pumps, the functional principle of which is based on deflecting a membrane or diaphragm, are generally not able to achieve sufficient dosing precision when dosing minute volume quantities, such as, for example, 1 nl (nanoliter) to 100 μl (microliters). In micromembrane pumps, the dosing precision is, for example, dependent on gas bubbles in the pump chamber, particles in the fluid, back pressure variations within the fluid channel, temperature variation and other influences.
Apart from the insufficient dosing precision of micromembrane pumps available at present, there are no systems, which may be implemented in an uncomplicated and thus cheap manner, to allow dosing and monitoring dosing of minute fluid quantities or fluid volumes in the nanoliter to microliter range. In addition, flow sensors, easy to implement, for the smallest volume packages in the nanoliter range have not been available up to now, or they do not have the accuracy needed for many applications, or are too expensive to integrate into the microdosing system. Apart from drug dosing mentioned above in medical technology, in many other fields of application, too, reliable and precise dosing and/or monitoring dosing of minute volume quantities are necessitated. Using liquid direct displacement devices in laboratory technology, charging the liquid fuel (such as, for example, methanol in DMFC=Direct Methanol Fuel Cell) in fuel cells or lubricant dosing in the form of lubricating bearings using oil are to be mentioned exemplarily in this regard.
In this context, reference is, for example, made to a liquid reservoir with level measurement and dosing system, withdrawal system and combined dosing/withdrawal system in the International publication WO01/84091 A1 and to the scientific publication “Dosierung and Messung kleiner Volumenströme als Voraussetzung für die Realisierung eines implantierbaren Mikroinfusionssystems” (Dosing and measuring small volumes streams as a requirement for realizing an implantable microinfusion system) by Bodo Nestler, et al., Zentrum für Biomedizintechnik der F H Lübeck in Impulse (10), 2005: ISSN 1618-5528, pages 65-73.